Sheet leveler



April 4, 1967 H. BIRKLE 3,312,094

SHEET LEVELER Filed Nov. 17, 1964 2 Sheets-Sheet 2 PRIOR ART INVENTOR.

HANS BIRKLE BY @wk .HlS AT ORNEY United States Patent Office 3,31.2,fi94 Patented Apr. 4, 1E6? 1 Claim. 61. 72-162) This inventionrelates to a sheet leveler having straightening rolls or roll trainsreceived in a frame, the rolls being adjustable in relation to oneanother, whereby the material to be leveled is passed between the rollsand straightened by directionally alternating and gradually diminishingthe deformations imparted to the material.

One design of a leveling machine known in the art included an uppertrain of straightening rolls mounted in a vertically adjustablecrossbeam which is received in a frame. Also included is a lower trainof straightening rolls preferably secured in a second frame. The outertop straightening rolls are constructed to be vertically adjustableindependently of the other rolls. In such a leveler, deformation of asheet, for example, passing between the first pair of rolls can bereduced to a lower value and by corresponding vertical adjustment of thelast straightening roll, the final sheet deformation can be regulated sothat the sheet travels in a direction straight out of the straighteningrolls.

In another sheet leveler the upper train of straightening rolls is notonly vertically adjustable but also arranged to be horizontallyswingable with respect to one another. In this leveler the sheet isheavily deformed at the entry side and, in accordance with the clearanceangle, the sheet deformations are decreasing from roll to roll.Permanent deformation beyond the yield point occurs only between thefirst pair of straightening rolls at the entry side while thedeformations effected by the succeeding pairs of straightening rollsgradually diminish towards a zero value.

With respect to the first mentioned leveler, permanent deformation isachieved by all the pairs of straightening rolls whereby a sheet leveledwith this machine contains considerable residual stresses that maydisturb subsequent processing. In the last mentioned sheet levelerdifficulties arise upon entrance of the sheet between the levelingrolls, especially in the case of heavier degrees of sheet deformation,because the first pair of rolls must perform the heaviest deformationwork. In addition, this leveler requires a relatively large number ofstraightening rolls to obtain the desired degree of leveling.

To eliminate the disadvantages of known sheet levelers, the presentinvention provides a leveler in which one of the opposite trains ofrolls is adjustable in relation to the other train through translationalmovement relative to the straightening plane. The rolls in said one rolltrain are arranged in two groups and carried by separate frames. Atleast the one of these roll groups is adjustable independently of theother one through swinging of its frame about an axis lying within theleveler and preferably in the central plane thereof. The invention alsoprovides that the said two groups of rolls have the same number ofstraightening rolls. In addition, it is advantageous to organize bothgroups of rolls mechanically independent of each other for horizontalswinging movement so as to permit any degree of adjustment for bothgroups.

The positioning of the frames carrying the two groups of straighteningrolls is advantageously so developed that the swivel axes of the framescoincide with the centers of rotation of two inner adjacentstraightening rolls of each frame.

Another feature of the present invention relates to providingindividually adjustable pivot drives for both groups of rolls that makeup one roll train and. an individual vertical adjustment drive for theother roll train. Means are provided for coupling together the pivotdrives of the two roll groups in the form of a coupling or an interposedtransmission member so that both simultaneous and individual adjustmentof the straightening rolls may be accomplished. Thus, upon reverseoperation of the drives, the existing angles of traverse of the rollgroups at the entry and delivery side may be automatically adjusted whena sheet is to be leveled while traveling in the reverse direction.

Further advantages may be obtained when one of the intermediatestraightening rolls or a backup roll associated therewith has its ownadjusting system independent of the adjustment of the otherstraightening roll. By adjustment and/or selection of the shape of thebackup roll, corrections can be made for partial stretching of a sheetto be leveled.

In a variant arrangement of the present invention, there is provided oneroll train fixedly arranged in the leveler frame while the other rolltrain received in two frames is arranged to be both verticallyadjustable in a direction normal to the straightening plane andhorizontally swingable. It is preferred, however, to employ an undividedroll train vertically adjustable in relation to the straightening plane,and as to the other train, it is divided into two groups, pivotallysupported within the leveler frame about different centers of rotation.

The foregoing features of the invention, as well as others, will becomemore evident from the following description and the attached drawings ofwhich:

FIGURE 1 is a schematic elevational view of a sheet leveler illustratingone embodiment of the present invention;

FIGURES 2 and 3 are force diagrams of two variable adjustments of thesheet leveler according to the invention; and

FIGURES 4 and 5 are force diagrams corresponding to FIGURES 2 and 3, butrepresentative of known sheet levelers.

With reference now to FIGURE 1, there is illustrated one side of a sheetleveler which includes a housing 1. Positioned within the upper portionof a window formed in this housing is a vertically adjustable frame 2which rotatably receives a train or plurality of straightening rolls 3.In order to simplify the disclosed embodiment of the present invention,backup rolls usually employed above the straightening rolls 3 are notshown in the drawings. The lower portion of the housing window is formedwith two opposed segmental surfaces onto which there are positionedcircular segmental frames 4 and 5 that rotatably receive a number ofstraightening rolls including rolls 6, 8 and 7, 9. Between these rollsand the train of rolls 3 passes a plane hereinafter referred to as thestraightening plane. The segment frames 4 and 5 each swing about pivotpoints which are near the straightening and central vertical planes ofthe leveler. In the illustrated embodiment the pivot points of theframes 4 and 5 coincide with the rotational axes of the rolls 8 and 9,respectively.

Operatively connected to the frames 4 and 5 are pivot drives havingmotors 10 and 11, worms 12 and 13, and worm wheels 14 and 15,respectively. Arranged on the shafts of the worm wheels are cams 16 and17 which are received into bores formed in sliding blocks 18 and 19 thatare in turn received in guides 20 and 21, re spectively.

Referring now to the frame 2 there is provided within the housing 1 ascrewdown 2 3 to adjust the vertical a position of the frame. Thisscrewdown is made up of t worm 24 and worm wheels 25 and 26 that areconnected .0 screws 27 and 28, respectively. The screws the engage theframe 2 and determine the height of the frame and train of rolls 3carried thereby.

With particular reference to the train of rolls 3 and :o the centralroll identified as 29, there is provided a Jackup roll 30 received in ayoke 31 which is in turn received in the frame 2 as shown in FIGURE 1. Aseparate vertical adjustment is provided for the roll 30 which includesa worm 32 connected to a worm wheel 33 received on a screw 34.

In the operation of the sheet leveler, the illustrated embodiment showsa sheet 22 passing from right to left as'one views FIGURE 1, coincidentwith the straightening plane and trains of rolls 3 and 6, 8 and 7, 9,respec- ;ively, Adjustment of the upper trains of rolls 3 and of :hetworoll groups 6, 8 and 7, 9 may be selected so that in the straighteningplane in the area of the roll group 7, 9 the sheet is flexed upwardlyand downwardly to such a. degree that plastic deformation of the sheetextends not only to the external sheet surface, but it is carried outclose to the neutral fiber, so that the sheet is prepared accordinglyfor the actual straightening effect. The group of straightening rolls 6,8 are positioned by the cam 16 so that deformation of the sheetdiminishes toward zero as the sheet passes from the last straighteningroll 6 at which time it is completely leveled. The residual stressesimposed by the plastic deformation in the zone of the roll group 7, 9are completely relieved by the alternative bending with decreasingmagnitudes in the zone of the roll group 6, 8.

Certain advantages of the present invention may be more fullyappreciated by viewing FIGURES 2 through in which each figure representsa diagram of the forces exerted upon a sheet being leveled. In theinterest of a simplification the average values of the forces acting onthe sheet within a leveler have been represented in the diagrams,therefore the diagrams do not represent the changing directions of theforces nor their pulsations duringthe passage of the sheet between thestraightening rolls.

FIGURE 2 shows a force diagram of the forces imposed on a sheet when therolls of the leveler are adjusted as illustrated in FIGURE 1. Whenentering the leveler, the sheet is subjected to rapidly rising forcescreated by the foremost rolls of the group of straightening rolls 3 and7, 9. When the forces reach a maximum in magnitude, the forces upon thesheet are adequate so that alternating plastic deformation is achieved.

The initial increasing forces are represented at 35 in FIGURE 2 andcorrespond to the entrance of the sheet in the leveler. The zone ofmaximum forces is represented at 36 while decreasing sheet deformationforces are represented at 37.

These decreasing forces occur when the end of the frame 4 carrying thestraightening roll is slightly lowered with respect to the horizontal,so that from the straightening roll 8 in the direction of the roll 6 thedeformations decrease linearily towards a zero value suificiently sothat the sheet emerges from the rolls 3 and 6, 8 fully straightened.

In the event it is desired to obtain greater sheet deformations, thetrain of rolls 3, including roll 29, are positioned in a downwarddirection by adjusting the screwdown 23. The group of straighteningrolls 7, 9 are then positioned at an incline or further inclined to thehorizontal plane by adjustment of the pivot drive motor 11. Theinclination of the rolls 7, 9 being such that the roll 7 is lower inelevation than roll 9. With the straightening roll so positioned, theforces imposed upon a sheet being leveled are represented by the diagramin FIGURE 3. The line 38 represents the forces upon the sheet during itsentry into the leveler. It will be noted that the magnitude of theseforces is less than the forces represented at 35 in FIGURE 2. Line 39represents the increasing forces that result in a plastic deformation.These forces become greater in magnitude than those represented at 36 inFIGURE 2 and result in greater sheet penetra tion of the plasticdeformation forces. Finally, in FIG URE 3, line 40 represents a decreasetoward zero in magnitude of forces upon the sheet. It is to beappreciated that the decrease in forces upon a unit of sheet lengthoccurs, with respect to the embodiment illustrated in FIGURE 1, afterthe sheet unit has passed from rolls 29 and/ or 8.

For the sake of comparison, force diagrams of conven= tional sheetlevelers are shown in FIGURES 4 and 5.- 7

The diagram illustrated in FIGURE 4 represents the; forces imposed upona sheet passing through a leveler having trains of straightening rollsadjustable in relation to one another and a separately adjustablestraightening roll arranged at the first and last positions of one rolltrain. In FIGURE 4 a relatively steep line 41 represents the forces uponthe sheet when entering the leveler. This line is followed by anextended zone of alternative deformations represented at 42, which areconstant in magnitude so that the plastic deformation per se appears tobe adequate. However, the forces upon the sheet passing from the levelerrepresented at 43 are reduced rapidly, and as a result, the lastback-fiexure of the sheet is straightened out without, as would bedesirable, imposing alternative sheet deformations with diminishingmagnitude.

In the diagram of FIGURE 5 the sheet flexing forces are imposed by thesheet leveler in which two opposite roll trains are verticallyadjustable and also horizontally shiftable in relation to one another.In this type of lev eler, an acute disadvantage is the very rapidincrease in the forces upon the sheet as represented by the line 44.This limits the amount of sheet deformation obtainable by such aleveler. After the sheet passes the first pair of rolls, deformation ofthe sheet diminishes slowly and without the plastic deformation. Suchdeformations are required, however, for the removal of stress in theideal straightening process.

With respect to the known sheet leveler arrangement characterized by theforce diagram in FIG-URE 5, it is necessary to provide a relativelylarge number of straightening rolls in order to achieve adequatestraightening and stress relieving of the sheet. The sheet leveleraccording to the present invention will obtain the desired properties inthe leveled sheets by employing a smaller number of straightening rollsthan sheet levelers based on the design according to the diagram ofFIGURE 5. Furthermore, sheet levelers according to the present inventionare more versatile and adaptable to a wider range of sheets and thelike, so that, for example, difiicu-lties during the run-in of thesheets can be avoided when heavier sheet deformations are to beperformed.

With reference now to the embodiment illustrated in FIGURE 1, aspreviously noted, a means is provided to so deflect the straighteningroll 29 so as to effect a working or stretching of a portion of thesheet being leveled. This is accomplished by controlling the manner inwhich the straightening roll 29 is supported so as to control itsdeflection. Such working or stretching, for example, can beadvantageously employed to remove an unflat or wavy condition of thestrip being leveled. The unflat condition is created when one portion ofa sheet is longer than an adjacent transverse portion. The means forcontrolling the deflection of the roll 29 includes the backup roll 30which is brought into contact with the straightening roll 29 by thescrew 34 so as to control the deflection of the roll 29. In the caseunder discussion, the working or stretching effect is exerted primarilyupon the middle portion of the sheet, thereby this portion will beelongated which will reduce or eliminate the waviness, in addition toimproving the overall results in the leveling process.

If, as illustrated in FIGURE 1, the backup roll 30 is substantiallyshorter than the straightening roll 29 and its position with respect tothe roll train 3 is not altered by the screwdown parts 32, 33 and 34,the result will be a simple deformation Without partial stretching. If,on the other hand, the backup roll 30 is retracted by its screwdown, itwill bend upwardly under the strain of the sheet being straightened, sothat the outer edges of the sheet to be straightened are stretched.

As heretofore indicated, variations of a sheet leveler according to thepresent invention can be obtained by employing the swingable frames 4and 5 which receive the groups of straightening rolls 6, 8 and "7, 9above the straightening plane and providing adjustment relative toheight. Additional straightening rolls can be provided in a framearranged intermediate the swing frames that receive the straighteningrolls.

The roll adjusting devices, i.e., screwdowns and pivot drives of thesheet leveler are preferably coupled together by control elementsarranged ahead of the leveler. In addition, it may be advantageous, withrespect to reversible sheet levelers, to exert control of the pivotdrives in such a manner that when the leveler is operated in the reversedirection, the pivot drives are reversed automatically, so that itsangular position of the frame 5 at the entry side can be obtained at thedelivery side, while the angular position of frame 4 is transmitted tothe entry side of this leveler. In this respect, it may be advisable tocouple the two pivot drives to indicate mechanically the settings insuch a way that, through a common adjusting process, alternativeadjustment of the setting angles is effected.

In certain forms of the present invention, it may be desirable toprovide a machine crown on the backup roll 30 to improve the overallresults of that portion of the present invention addressed to reducingor eliminating the unfiat condition of the strip, whether it be in thecenter of the strip or on the two edges thereof.

In accordance with the provisions of the patent statutes, I haveexplained the principle and operation of my invention and haveillustrated and described what I consider to represent the bestembodiment thereof. However, I desire to have it understood that withinthe scope of the appended claim, the invention may be practicedotherwise than as specifically illustrated and described.

I claim:

In a leveler for straightening sheet material and the like comprising:

a housing having a window formed therein;

first and second trains of straightening rollers, each comprising aplurality of spaced-apart rollers received in said window;

said first train arranged in an opposed relationship with respect tosaid second train so that the rollers of each train are arranged in anested relationship, said opposed trains of rollers being arranged toform a straightening plane therebetween;

first frame received in said window for rotatably supporting said firsttrain of roliers;

a screwdown carried by said housing for positioning said first frame andthe rollers carried thereby in a direction normal to said straighteningplane;

second and third frames pivotally received in said window for rotatablysupporting said second train;

means for positioning said second and third frames about axes lying nearto the point of intersection of the vertical center plane of the levelerand the straightening plane, whereby selective positioning of therollers of said second and third frames relative to the rollers of saidfirst train creates alternatively first and second zones, one being ofan appreciable length wherein high sheet deformation takes place and theother a zone of gradual varying deformation;

a single backup roller arranged with its axis coinciding substantiallywith the vertical center plane of said leveler and engageable with oneof said straightening rollers of said first train to control the shapethereof along its axis for differentially stretching a sheet beingleveled to reduce waviness in the sheet; and

a second screwdown for adjusting the backup roller relative to said onestraightening roller of said first train References ited by the ExaminerUNITED STATES PATENTS 2,132,426 10/1938 Maussnest 72-463 2,638,1435/1953 Maust 72--163 2,827,945 3/1958 Maust 72163 FOR *IGN PATENT S919,945 11/1954 Germany.

CHARLES W. LANHAM, Primary Examiner. R. D. GREFE, Assistant Examiner.

